1. Field of the Invention
This invention relates to an infrared radiation thermometer, in particular a tympanic thermometer, in which a sensor detecting infrared radiation and having an electronic evaluation circuitry associated therewith is arranged in a housing having a radiation inlet, in which for temperature measurement the radiation inlet is covered with a detachable probe cover sufficiently transparent to infrared radiation, and in which the absence of a probe cover is detected by a sensor issuing a warning signal after the thermometer is switched on.
2. The State of the Art
Infrared radiation thermometers of the type initially referred to are used for measuring body temperature in both a domestic and a medical environment. Typically, such a radiation thermometer includes a housing with a window admitting radiation, an optical waveguide or an optical power collecting arrangement, and an infrared sensor which is connected to an electronic evaluation unit. The IR window serves the function of closing off the interior of the housing of the radiation thermometer, thereby protecting the optical components and the infrared sensor from contamination and irreparable damage.
In order to prevent in particular the transmission of diseases due to failure to maintain sanitary conditions, it has become common practice to fit a probe cover over the IR window which comprises a window section fixedly connected to the infrared optic system, thus preventing the entry of contaminants. This enables ready replacement of the probe cover which is advantageously a deep-drawn component transmitting infrared radiation well and having a very thin area for the passage of light as, for example, in the form of a film or a film-type section.
In order to prevent the measurements referred to in the foregoing from being performed without a probe cover installed, known tympanic thermometers have been equipped with an evaluation unit detecting, for example, the absence of a probe cover and indicating such absence on an indicating device. Thus, for example, an infrared radiation thermometer is known from EP-A-0 565 123 in which a measurement without the probe cover installed cannot be performed.